Noble metal ions, such as, silver and gold ions, are known to be antimicrobial and have been used in medical care to prevent and to treat infection. In recent years, that technology has been applied to consumer products to prevent transmission of infectious disease and to kill harmful bacteria, such as, Staphylococcus and Salmonella. In common practice, noble metals, metal ions, metal salts or compounds containing metal ions having antimicrobial properties can be applied to surfaces to impart an antimicrobial property to the surface. If, or when, the surface is inoculated with harmful microbes, the antimicrobial metal ions or metal complexes, in effective concentration, slow or prevent growth of those microbes.
In the context of antimicrobial coatings, colloidal silver has been indicated to work as a catalyst disabling a metabolic enzyme of bacteria, fungi and viruses. Many pathogens can be eradicated effectively in presence of even minute traces of silver. Indeed colloidal silver is effective against more than 650 different disease-causing pathogens. Unlike antibiotics, strains resistant to silver have yet to be identified.
There remains a need for printed labels on medical devices and consumer products with an antimicrobial property. Toner is used for printing labels, security marks, clear coats and other applications of 2-dimensional surfaces or structures, and toner-like compositions are used for 3-dimensional applications creating structures and devices.
The use of organic biocide in materials, such as, polymers, inks, toners etc. is known (U.S. Pat. No. 6,210,474) however, those biocide agents do not demonstrate antimicrobial effectiveness within the printed or, “coated,” state, such as, in printed ink or toner. Those biocide agents are used generally as a preservative to stabilize material, e.g. polymer, prior to use in preparation of inks and toners, wherein the agent is present in the final ink or toner product in amounts insufficient to impart antimicrobial activity to the printed image made with the ink or toner.
Microorganisms, which include, but are not limited to bacteria, fungi or algae, for example, can be obtained from typical handling of objects, and airborne microbes (sneezing, coughing or other forms of aerosolization) can be spread by vectors, carriers and infected hosts. Hence, images or structures containing antimicrobial toner would be useful in, for example, restaurants (menus), businesses (legal documents) and hospitals (charts, memos, pictures, labels and devices).
Therefore, new antibacterial or antimicrobial toner particles are needed for forming coatings, images, structures or devices wherein contact of microbes with the image, coating, structure or device will inhibit growth and destroy colonization of the microbes.